testimonial vs commendation

testimonial and commendation both are nouns.

Word	Noun	Adjective	Verb	Adverb
testimonial	Yes	Yes	No	No
commendation	Yes	No	No	No

As nouns, commendation is a hypernym of testimonial; that is, commendation is a word with a broader meaning than testimonial:

Other hypernyms of testimonial include approval.

testimonial (noun)	commendation (noun)
something that recommends (or expresses commendation of) a person or thing as worthy or desirable	an official award (as for bravery or service) usually given as formal public statement
something given or done as an expression of esteem	a message expressing a favorable opinion
something that serves as evidence

testimonial (adjective)	commendation (adjective)
of or relating to or constituting testimony
expressing admiration or appreciation